Smelting and casting method of sulfur-containing and aluminum-containing gear steel

Abstract

The invention discloses a smelting and casting method of sulfur-containing and aluminum-containing gear steel. The method comprises sequential steps as follows: (1), electric furnace or converter smelting; (2), LF refining; (3), VD or RH vacuum treatment; and (4), continuous casting. According to the method, in step (1), Al element is added during steel tapping, Al content of molten steel is enabled to reach 0.03wt%-0.05wt%; and furthermore, S element in the molten steel at the smelting end is controlled to in a range of 0.015wt%-0.035wt%; in step (2), following slag components are controlled:45wt%-55wt% of CaO, 20wt%-35wt% of Al2O3, 5wt%-10wt% of MgO and 10wt%-25wt% of SiO2; and in step (3), the Al element is added to the molten steel again after vacuum breaking, so that Al content of the molten steel reaches 0.03wt%-0.05wt%. When the smelting and casting method is used for smelting and casting, water nozzle clogging in a casting process can be effectively prevented.

Description

technical field [0001] The invention relates to a smelting and casting method, in particular to a steel smelting and casting method. Background technique [0002] Gear steel is one of the key materials used in large quantities and with high requirements in automotive materials. It affects various important technical and economic indicators such as vehicle life and energy consumption. In order to ensure processing performance and prevent grain growth, the content of aluminum and sulfur in gear steel is relatively high, and high melting point inclusions (such as Al 2 o 3 and MgO-Al 2 o 3 Inclusions) cause nozzle nodulation. [0003] Generally for this, the treatment method in the prior art is to perform calcium treatment to convert the high melting point inclusions in the steel into low melting point inclusions. [0004] For example: in the technical scheme disclosed in the Chinese patent document whose publication number is CN104212940A, the publication date is December ...

AI Technical Summary

Problems solved by technology

[0006] However, the above-mentioned technical solutions in the prior art will lead to the appearance of large Ds inclusions in steel grades (Ds inclusions refer to round or nearly round single particle inclusions with a diameter ≥ 13 μm), and these large Ds inclusions seriously affect Its fatigue life and cutting performance

In addition, when the sulfur content in steel is high, calcium treatment can easily generate new high melting point inclusions CaS, which will lead to nozzle blockage

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